Did you see the full video. HIS KNEE WAS NOT ON HIS NECK!
And there was no sign of trauma to his neck. Propaganda spread by the mob.
No, I haven’t seen any video, but how long before you called uncle if he was on your back? And you’re probably not in poor condition. A lot of heavy people have trouble breathing or are out of breath just standing up.
The fact he managed to vocalize “I can’t breathe” several times does not mean he was getting sufficient oxygen.